Israeli tank in Beirut in 1982. Photograph: David Rubinger/Time & Life Pictures/Getty Image

It's reasonable to describe journalism as the "first rough draft of history," and always interesting, when secret government documents are released, to see how far that early version stands the test of time. The Falklands conflict with Argentina dominated the headlines about British state papers declassified from 1982 – the traditional three decades after the event. But those dealing with that year's Lebanon war provide some fascinating and still relevant insights. The war began in a sense in London, where, on June 3, a Palestinian gunman shot the Israeli ambassador, Shlomo Argov. It was clear from the start that the hit team was not from the PLO but from the dissident Iraqi-backed outfit run by Abu Nidal, Yasser Arafat's sworn enemy. Israel's prime minister, Menachem Begin, egged on by his defence minister, Ariel Sharon, went to war against the PLO in Lebanon anyway. "Abu Nidal, Abu Shmidal," another Israeli minister said.

The documents generated at the time by British embassies, the foreign office and Downing Street provide evidence of continuity and change at a crucial moment.

Margaret Thatcher, fresh from her Falklands triumph, refused to talk to the PLO on the grounds that it had neither recognized Israel nor renounced terrorism. But there was movement nevertheless: Thatcher received an Arab League ministerial delegation but allowed Douglas Hurd, a foreign office minister, to meet Farouq Qaddoumi, Arafat's foreign minister. It was the first encounter of its kind and a landmark on the way to international recognition of an organization whose hard-fought claim to be the "sole legitimate representative" of the Palestinians must now be in doubt.

"A balance would thus be struck between the United Kingdom's sympathy with the Arabs over the Israeli invasion of the Lebanon and the fact that the Israeli Ambassador in London, Mr Argov, had been attacked by a splinter group of the PLO," the secret cabinet minutes recorded.

Britain's Arab friends looked on in alarm as the crisis deepened, the documents show. King Hussein of Jordan was terrified that Palestinians would be driven from Lebanon into his own security-conscious realm. Only those with Jordanian passports would be admitted and only after being "thoroughly screened to weed out undesirables." Hussein warned Thatcher of an "unprecedented holocaust" and a "bloodbath."

In Cairo Hosni Mubarak, just a few months in office, was horrified at the idea that the PLO might set up a government-in-exile in Egypt. The then (as now) Saudi foreign minister Saud al-Faisal lobbied Thatcher to use her influence with Ronald Reagan. But she declined a suggestion that she ask the US president to pressure the Israelis not to enter west Beirut –as they eventually did.

Then, as now, Washington was where things happened, and it was American envoys who tried to cobble together a ceasefire. There was also some discomfort. "The Americans are concerned at the extent to which the Israelis have misled them at every stage of their Lebanese operation," the British ambassador reported after meeting Alexander Haig, Reagan's secretary of state. "There are continuing divisions within the administration but it looks increasingly likely that, as usual, the pro-Israeli faction will have its way."

Brian Urquhart, a senior British UN official, had a "blazing row" with a US diplomat and demanded pressure on the Israelis to allow humanitarian access since "the Americans and the other Arabs were apparently not prepared to do anything in the face of what looked like mass murder of the Palestinians by the Israelis."

Like many government documents these British papers confirm what was widely reported at the time about a conflict which has always attracted intense media attention. Still, even in the post-WikiLeaks era there is a frisson in reading confidential reports and reflections, some of them piercingly perceptive. Small indiscretions – about French arrogance, Israeli influence over the US, Arab frustration and British manoeuvring – add colour, nuance and understanding to enrich the historical record.

Of the Lebanon war material released so far by the National Archives, the most riveting document is a secret "UK Eyes Alpha" assessment by the Joint Intelligence Committee on June 22 1982. Its insights remain valid, mutatis mutandis, to this day.

"Much of the Arab world sincerely believes that the United States administration had connived in, if not positively blessed, the Israeli invasion. Many of the moderate Arab leaders, including the Jordanians, Saudis and Egyptians are dismayed that the United States has failed to use its leverage over Israel effectively to deter new aggression and to prevent occupation of more Arab land. The perception that the United States has acquiesced in the Israeli action will be seen as evidence of double standards when the administration is condemning the use of force to settle disputes in other parts of the world.

"It will undermine faith in United States ability and willingness to defend other moderate Arab states from Iranian as well as Israeli aggression. It has all but destroyed, for the time being, Arab faith in the willingness of the United States to use its leverage with Israel to obtain a solution to the Palestinian problem which takes account of Arab needs."